[chimerax-users] Macbook Pro, fans, and ChimeraX

[Tom Goddard]

Hi Lewis,

  On my I 2021 MacBook Pro M1 Max with macOS 13.1 if I open a large model and spin it in ChimeraX daily build I also see 200% CPU and about 36% GPU in Mac Activity Monitor.

	open 8dit
	show atoms
	roll

But I never hear a fan, in fact I don't recall ever hearing the fan on this machine.  If I also use ambient shadows the GPU use goes up to 72% during the spin

	light full

If I stop the spin (command stop) then the CPU use goes to 2% and GPU use to 1%.   ChimeraX uses the GPU heavily for rendering graphics.  I see the same CPU and GPU use for an old ChimeraX version 1.3.  I don't know why ChimeraX is using 200% CPU.  That is surprising.  I suspect that reported CPU use is somehow misleading and it would be worth checking on Windows or Linux to see what they say the CPU use is.  ChimeraX in general does very few tasks with multiple threads, and only one thread is rendering, so I think it is something peculiar about macOS that it is report 200% CPU use.  Maybe using the GPU automatically engages a new CPU thread.  I recall in years past CPU use was minimal (20%?) and GPU use depended on complexity of rendering (5 to 100%) for moving a model.

  I had a 2019 Intel MacBook Pro and I recall its fans went crazy loud for no apparent reason, and it was not entirely predictable.  That machine failed in less than 2 years due to the display hinge cable wearing out.  I never figured out its loud fan issues.  I recall them going away maybe after some macOS update.

	Tom




> On Jan 24, 2023, at 8:22 PM, Lewis James martin via ChimeraX-users <chimerax-users at cgl.ucsf.edu> wrote:
> 
> Hi all, 
> Ever since I got my Macbook Pro (16-inch, 2019, 2.3GHz 8‑core Intel Core i9) I noticed the fans can go full bore for seemingly small tasks. ChimeraX is one of those - swinging a protein view around is enough to set them off, and Activity Monitor reports around 200% usage for the "UCSF ChimeraX" process. I can see that GPU usage on the inbuilt AMD Radeon Pro 5500M can get up to about 50%, too. The bottom can get quite hot - it's Summer here now, but this happens in Winter too. 
> 
> A couple of questions:
> - Is this expected (for ChimeraX, not generally)? Do other people experience this? 
> - Does ChimeraX use the GPU for rendering? If so, what's driving the CPU spike when I move the protein on screen? Is it just from calculating the coordinate rotations?
> 
> Thanks, 
> Lewis
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